Update rethrow depth handling and catch_all opcode (#1608)

Give `catch_all` its own opcode:

Previously `catch_all` shared an opcode with `else`, but
the spec now allocates it the 0x19 opcode.

Adjust rethrow depth semantics:

Previously this had interpreted the rethrow depth argument
as counting only catch blocks, but the spec has clarified that
it should count all blocks (in a similar fashion as `br` and
related instructions).

15 files changed, 36 insertions, 25 deletions

diff --git a/src/binary-reader-ir.cc b/src/binary-reader-ir.cc
index 53a52233..cdda3311 100644
--- a/src/binary-reader-ir.cc
+++ b/src/binary-reader-ir.cc
@@ -145,6 +145,7 @@ class BinaryReaderIR : public BinaryReaderNop {
                        Index default_target_depth) override;
   Result OnCallExpr(Index func_index) override;
   Result OnCatchExpr(Index event_index) override;
+  Result OnCatchAllExpr() override;
   Result OnCallIndirectExpr(Index sig_index, Index table_index) override;
   Result OnReturnCallExpr(Index func_index) override;
   Result OnReturnCallIndirectExpr(Index sig_index, Index table_index) override;
@@ -759,8 +760,6 @@ Result BinaryReaderIR::OnElseExpr() {
     if_expr->true_.end_loc = GetLocation();
     label->exprs = &if_expr->false_;
     label->label_type = LabelType::Else;
-  } else if (label->label_type == LabelType::Try) {
-    return AppendCatch(Catch(GetLocation()));
   } else {
     PrintError("else expression without matching if");
     return Result::Error;
@@ -1007,6 +1006,10 @@ Result BinaryReaderIR::OnCatchExpr(Index except_index) {
   return AppendCatch(Catch(Var(except_index, GetLocation())));
 }
 
+Result BinaryReaderIR::OnCatchAllExpr() {
+  return AppendCatch(Catch(GetLocation()));
+}
+
 Result BinaryReaderIR::OnUnwindExpr() {
   LabelNode* label = nullptr;
   CHECK_RESULT(TopLabel(&label));
diff --git a/src/binary-reader-logging.cc b/src/binary-reader-logging.cc
index 2c2d1e7f..5cebbe92 100644
--- a/src/binary-reader-logging.cc
+++ b/src/binary-reader-logging.cc
@@ -794,6 +794,7 @@ DEFINE_OPCODE(OnBinaryExpr)
 DEFINE_INDEX_DESC(OnCallExpr, "func_index")
 DEFINE_INDEX_INDEX(OnCallIndirectExpr, "sig_index", "table_index")
 DEFINE_INDEX_DESC(OnCatchExpr, "event_index");
+DEFINE0(OnCatchAllExpr);
 DEFINE_OPCODE(OnCompareExpr)
 DEFINE_OPCODE(OnConvertExpr)
 DEFINE_INDEX_DESC(OnDelegateExpr, "depth");
diff --git a/src/binary-reader-logging.h b/src/binary-reader-logging.h
index 30dc0712..70dcbae6 100644
--- a/src/binary-reader-logging.h
+++ b/src/binary-reader-logging.h
@@ -164,6 +164,7 @@ class BinaryReaderLogging : public BinaryReaderDelegate {
                        Index default_target_depth) override;
   Result OnCallExpr(Index func_index) override;
   Result OnCatchExpr(Index event_index) override;
+  Result OnCatchAllExpr() override;
   Result OnCallIndirectExpr(Index sig_index, Index table_index) override;
   Result OnCompareExpr(Opcode opcode) override;
   Result OnConvertExpr(Opcode opcode) override;
diff --git a/src/binary-reader-nop.h b/src/binary-reader-nop.h
index 1f29a670..f72dbf10 100644
--- a/src/binary-reader-nop.h
+++ b/src/binary-reader-nop.h
@@ -234,6 +234,7 @@ class BinaryReaderNop : public BinaryReaderDelegate {
   Result OnCallExpr(Index func_index) override { return Result::Ok; }
   Result OnCallIndirectExpr(Index sig_index, Index table_index) override { return Result::Ok; }
   Result OnCatchExpr(Index event_index) override { return Result::Ok; }
+  Result OnCatchAllExpr() override { return Result::Ok; }
   Result OnCompareExpr(Opcode opcode) override { return Result::Ok; }
   Result OnConvertExpr(Opcode opcode) override { return Result::Ok; }
   Result OnDelegateExpr(Index depth) override { return Result::Ok; }
diff --git a/src/binary-reader-objdump.cc b/src/binary-reader-objdump.cc
index f03283e7..11fba30b 100644
--- a/src/binary-reader-objdump.cc
+++ b/src/binary-reader-objdump.cc
@@ -596,6 +596,7 @@ void BinaryReaderObjdumpDisassemble::LogOpcode(size_t data_size,
       switch (current_opcode) {
         case Opcode::Else:
         case Opcode::Catch:
+        case Opcode::CatchAll:
         case Opcode::Unwind:
           indent_level--;
         default:
diff --git a/src/binary-reader.cc b/src/binary-reader.cc
index 495de306..9b365e87 100644
--- a/src/binary-reader.cc
+++ b/src/binary-reader.cc
@@ -1341,6 +1341,12 @@ Result BinaryReader::ReadFunctionBody(Offset end_offset) {
         break;
       }
 
+      case Opcode::CatchAll: {
+        CALLBACK(OnCatchAllExpr);
+        CALLBACK(OnOpcodeBare);
+        break;
+      }
+
       case Opcode::Unwind: {
         CALLBACK0(OnUnwindExpr);
         CALLBACK0(OnOpcodeBare);
diff --git a/src/binary-reader.h b/src/binary-reader.h
index 6ba4c9b7..19643aa8 100644
--- a/src/binary-reader.h
+++ b/src/binary-reader.h
@@ -231,6 +231,7 @@ class BinaryReaderDelegate {
   virtual Result OnCallExpr(Index func_index) = 0;
   virtual Result OnCallIndirectExpr(Index sig_index, Index table_index) = 0;
   virtual Result OnCatchExpr(Index event_index) = 0;
+  virtual Result OnCatchAllExpr() = 0;
   virtual Result OnCompareExpr(Opcode opcode) = 0;
   virtual Result OnConvertExpr(Opcode opcode) = 0;
   virtual Result OnDelegateExpr(Index depth) = 0;
diff --git a/src/binary-writer.cc b/src/binary-writer.cc
index 6ef3e71d..c744aca4 100644
--- a/src/binary-writer.cc
+++ b/src/binary-writer.cc
@@ -976,7 +976,7 @@ void BinaryWriter::WriteExpr(const Func* func, const Expr* expr) {
         case TryKind::Catch:
           for (const Catch& catch_ : try_expr->catches) {
             if (catch_.IsCatchAll()) {
-              WriteOpcode(stream_, Opcode::Else);
+              WriteOpcode(stream_, Opcode::CatchAll);
             } else {
               WriteOpcode(stream_, Opcode::Catch);
               WriteU32Leb128(stream_, GetEventVarDepth(&catch_.var),
diff --git a/src/interp/interp.cc b/src/interp/interp.cc
index ce1897bb..5988be1e 100644
--- a/src/interp/interp.cc
+++ b/src/interp/interp.cc
@@ -1736,6 +1736,7 @@ RunResult Thread::StepInternal(Trap::Ptr* out_trap) {
 
     case O::Try:
     case O::Catch:
+    case O::CatchAll:
     case O::Unwind:
     case O::Delegate:
     case O::Throw:
diff --git a/src/interp/istream.cc b/src/interp/istream.cc
index 6c531a88..6e956675 100644
--- a/src/interp/istream.cc
+++ b/src/interp/istream.cc
@@ -693,6 +693,7 @@ Instr Istream::Read(Offset* offset) const {
 
     case Opcode::Block:
     case Opcode::Catch:
+    case Opcode::CatchAll:
     case Opcode::Delegate:
     case Opcode::Else:
     case Opcode::End:
diff --git a/src/opcode-code-table.c b/src/opcode-code-table.c
index 6a746c5e..c3e06d03 100644
--- a/src/opcode-code-table.c
+++ b/src/opcode-code-table.c
@@ -27,7 +27,6 @@ typedef enum WabtOpcodeEnum {
 #include "opcode.def"
 #undef WABT_OPCODE
   Invalid,
-  CatchAll = Else,
 } WabtOpcodeEnum;
 
 WABT_STATIC_ASSERT(Invalid <= WABT_OPCODE_CODE_TABLE_SIZE);
diff --git a/src/opcode.def b/src/opcode.def
index 2156f118..0c661c19 100644
--- a/src/opcode.def
+++ b/src/opcode.def
@@ -56,6 +56,7 @@ WABT_OPCODE(___,  ___,  ___,  ___,  0,  0,    0x11, CallIndirect, "call_indirect
 WABT_OPCODE(___,  ___,  ___,  ___,  0,  0,    0x12, ReturnCall, "return_call", "")
 WABT_OPCODE(___,  ___,  ___,  ___,  0,  0,    0x13, ReturnCallIndirect, "return_call_indirect", "")
 WABT_OPCODE(___,  ___,  ___,  ___,  0,  0,    0x18, Delegate, "delegate", "")
+WABT_OPCODE(___,  ___,  ___,  ___,  0,  0,    0x19, CatchAll, "catch_all", "")
 WABT_OPCODE(___,  ___,  ___,  ___,  0,  0,    0x1a, Drop, "drop", "")
 WABT_OPCODE(___,  ___,  ___,  I32,  0,  0,    0x1b, Select, "select", "")
 WABT_OPCODE(___,  ___,  ___,  I32,  0,  0,    0x1c, SelectT, "select", "")
diff --git a/src/opcode.h b/src/opcode.h
index 80d3181b..94cd4cb8 100644
--- a/src/opcode.h
+++ b/src/opcode.h
@@ -39,7 +39,6 @@ struct Opcode {
 #include "src/opcode.def"
 #undef WABT_OPCODE
     Invalid,
-    CatchAll = Else,
   };
 
 // Static opcode objects.
diff --git a/src/type-checker.cc b/src/type-checker.cc
index 9136442b..40325fac 100644
--- a/src/type-checker.cc
+++ b/src/type-checker.cc
@@ -71,28 +71,26 @@ Result TypeChecker::GetLabel(Index depth, Label** out_label) {
 }
 
 Result TypeChecker::GetRethrowLabel(Index depth, Label** out_label) {
-  Index cur = 0, catches = 0;
-  std::string candidates;
+  if (Failed(GetLabel(depth, out_label))) {
+    return Result::Error;
+  }
+
+  if ((*out_label)->label_type == LabelType::Catch) {
+    return Result::Ok;
+  }
 
-  while (cur < label_stack_.size()) {
-    *out_label = &label_stack_[label_stack_.size() - cur - 1];
-
-    if ((*out_label)->label_type == LabelType::Catch) {
-      if (catches == depth) {
-        return Result::Ok;
-      } else {
-        if (!candidates.empty()) {
-          candidates.append(", ");
-        }
-        candidates.append(std::to_string(catches));
-        catches++;
+  std::string candidates;
+  for (Index idx = 0; idx < label_stack_.size(); idx++) {
+    LabelType type = label_stack_[label_stack_.size() - idx - 1].label_type;
+    if (type == LabelType::Catch) {
+      if (!candidates.empty()) {
+        candidates.append(", ");
       }
+      candidates.append(std::to_string(idx));
     }
-
-    cur++;
   }
 
-  if (catches == 0) {
+  if (candidates.empty()) {
     PrintError("rethrow not in try catch block");
   } else {
     PrintError("invalid rethrow depth: %" PRIindex " (catches: %s)", depth,
diff --git a/src/wat-writer.cc b/src/wat-writer.cc
index fd102130..cdea3b1b 100644
--- a/src/wat-writer.cc
+++ b/src/wat-writer.cc
@@ -881,9 +881,7 @@ Result WatWriter::ExprVisitorDelegate::OnCatchExpr(
     TryExpr* expr, Catch* catch_) {
   writer_->Dedent();
   if (catch_->IsCatchAll()) {
-    // We use a literal instead of doing GetName() on the opcode because
-    // `else` and `catch_all` share an opcode.
-    writer_->WritePutsNewline("catch_all");
+    writer_->WritePutsNewline(Opcode::CatchAll_Opcode.GetName());
   } else {
     writer_->WritePutsSpace(Opcode::Catch_Opcode.GetName());
     writer_->WriteVar(catch_->var, NextChar::Newline);